Orientation layer for directed self-assembly patterning process

ABSTRACT

Disclosed is a method of forming a semiconductor device using a self-assembly (DSA) patterning process. The method includes forming a patterned feature over a substrate; applying an orientation material that includes a first polymer and a second polymer over the substrate, wherein the first polymer has a first activation energy and the second polymer has a second activation energy; baking the substrate at first temperature thereby forming a first orientation layer that includes the first polymer; baking the substrate at second temperature thereby forming a second orientation layer that includes the second polymer; and performing a directed self-assembly (DSA) process over the first and the second orientation layers.

BACKGROUND

The semiconductor integrated circuit (IC) industry has experiencedexponential growth. Technological advances in IC materials and designhave produced generations of ICs where each generation has smaller andmore complex circuits than the previous generation. In the course of ICevolution, functional density (i.e., the number of interconnecteddevices per chip area) has generally increased while geometry size(i.e., the smallest component (or line) that can be created using afabrication process) has decreased. This scaling down process generallyprovides benefits by increasing production efficiency and loweringassociated costs. Such scaling down has also increased the complexity ofprocessing and manufacturing ICs.

For example, as optical lithography approaches its technological andeconomical limits, a directed self-assembly (DSA) process emerges as apotential candidate for patterning dense features. A DSA process takesadvantage of the self-assembling properties of materials, such as blockcopolymers (BCP), to reach nano scale dimensions while meeting theconstraints of current manufacturing. However, while existing DSAprocesses have been generally adequate for their intended purposes, theyhave not been entirely satisfactory in every aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 shows a flow chart of a method of fabricating a semiconductordevice, according to various aspects of the present disclosure.

FIGS. 2A-2E are cross sectional views of forming a semiconductor deviceaccording to the method of FIG. 1 in accordance with some embodiments.

FIG. 3 shows a schematic view of the orientation material that is usedin the method of FIG. 1 in accordance with some embodiments.

FIG. 4 shows a flow chart of a method of fabricating a semiconductordevice, according to various aspects of the present disclosure.

FIGS. 5A-5E are cross sectional views of forming a semiconductor deviceaccording to the method of FIG. 4 in accordance with some embodiments.

FIG. 6 shows a schematic view of the orientation material that is usedin the method of FIG. 4 in accordance with some embodiments.

FIG. 7 shows a flow chart of a method of fabricating a semiconductordevice, according to various aspects of the present disclosure.

FIGS. 8A-8F are cross sectional views of forming a semiconductor deviceaccording to the method of FIG. 1 in accordance with some embodiments.

FIG. 9 shows a schematic view of the orientation material that is usedin the method of FIG. 7 in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The present disclosure is generally related to semiconductor devices,and more particularly to methods for manufacturing semiconductor deviceswith dense and nanoscale patterns. When fabricating dense patterns, adirected self-assembly (DSA) process may be used to enhance and augmentthe existing semiconductor manufacturing capabilities. In a typical DSAprocess, a block copolymer (BCP) film is formed over lithographicallydefined surfaces and a microphase separation is induced to cause theconstituent polymer molecules to self-assemble, thus creating denselypacked features with uniform dimensions and shapes. A BCP film or simplya BCP includes polymers comprised of at least two different polymersegments. These polymer segments are configured to assemble themselvesinto highly ordered structures under certain conditions such as forexample, when they are exposed to an elevated temperature. In general, aneutral layer or an orientation layer is disposed on a surface of asubstrate of a lithographically defined surface before forming the BCPfilm. The neutral layer has no affinity for either of the polymersegments of the BCP film. During a DSA process, the neutral layer may beable to lead/orientate a first polymer segment for directedself-assembly. However, in order to orientate a second polymer segmentfor directed self-assembly, at least one additional process (e.g.,forming another neutral layer using the additional process to orientatethe second polymer segment) is required. The forming the another neutrallayer generally includes multiple process to be involved such as forexample, removing part of the neutral layer that leads the first polymersegment, providing a pattern for the neutral layer that is to lead thesecond polymer segment, and removing the patterned neutral layer. Incontrast, the present disclosure provides various embodiments of amethod to form an improved neutral layer without requiring theabove-identified additional processes.

Referring now to FIG. 1, a flow chart of a method 100 of forming asemiconductor device is illustrated according to various aspects of thepresent disclosure. Additional operations can be provided before,during, and after the method 100, and some operations described can bereplaced, eliminated, or moved around for additional embodiments of themethod. The method 100 is briefly described below. Then, someembodiments of the method 100 will be described in conjunction withFIGS. 2A, 2B, 2C, 2D, 2E, and 3.

Referring to FIGS. 1 and 2A, the method 100 begins at operation 102 byproviding a substrate 202 with a pattern 204. The substrate 202 mayinclude one or more layers of material or composition. For example, thesubstrate 202 may include an elementary semiconductor, such as siliconand germanium. The substrate 202 may also include a compoundsemiconductor such as silicon carbide, gallium arsenic, indium arsenide,and indium phosphide. The substrate 202 may include an alloysemiconductor such as silicon germanium, silicon germanium carbide,gallium arsenic phosphide, and gallium indium phosphide. The substrate202 may also include an epitaxial layer. For example, the substrate 202may have an epitaxial layer overlying a bulk semiconductor. Furthermore,the substrate 202 may include a semiconductor-on-insulator (SOI)structure. For example, the substrate 202 may include a buried oxide(BOX) layer formed by a process such as separation by implanted oxygen(SIMOX) or other suitable technique, such as wafer bonding and grinding.In some other embodiments, the substrate 202 may further include a toplayer (not shown) overlaying a top surface of the substrate 202. Assuch, the top layer may include silicon oxide, silicon nitride,oxynitride, silicon carbide, titanium oxide, titanium nitride, tantalumoxide, tantalum nitride, and/or any suitable materials.

In the illustrated embodiment of FIG. 2A, pattern 204 may be a resistlayer (e.g., a photoresist layer). The resist layer may be a positiveresist or a negative resist, and may be a resist suitable for deepultraviolet (DUV), extreme ultraviolet (EUV), electron beam (e-beam),and/or other lithography processes. In some specific embodiments,pattern 204 is formed of organic materials. While still falling withinthe scope of the present disclosure, the pattern 204 may be formed ofone of a variety of materials that is suitable for forming a pattern.The pattern 204 may be formed by any suitable methods such as forexample, a chemical vapor deposition (CVD) process, an atomic layerdeposition (ALD) process, a spin-on coating, and/or any combinationthereof.

Referring still to FIG. 2A, the substrate 202 includes an exposed topsurface 203, and the pattern 204 includes a sidewall 205. According tothe current embodiments, the top surface 203 of the substrate 202 andthe sidewall 205 of the pattern 204 each includes a different surfacecharacteristic. For example, the top surface 203 includes an oxidizedsurface which is more reactive while the sidewall 205 includes a surfacethat is formed of organic materials which is less reactive.

Referring to FIG. 1, the method 100 proceeds to operation 104 byproviding an orientation layer that is formed of at least two polymers(e.g., a first polymer and a second polymer). In an embodiment, asillustrated in FIG. 3, the orientation layer includes a first polymer302 and a second polymer 304. More specifically, the first polymer 302includes a polymer backbone 302′ and at least an atom/unit of thebackbone 302′ is replaced with or modified by a group 303; and thesecond polymer 304 includes a polymer backbone 304′ and at least anatom/unit of the backbone 304′ is replaced with or modified by a group305. The group 303 is a hydroxyl group with a higher amount of carbonside chains (e.g., carbon side chains >4) and the group 305 is ahydroxyl group with a lower amount of carbon side chains (e.g., carbonside chains <2). As such, the first polymer 302 may have a loweractivation energy than the second polymer 304 may have. That is, thefirst polymer 302 with the lower activation energy may be activated at afirst elevated temperature and the second polymer 304 with the higheractivation energy may be activated at a second elevated temperature,wherein the first elevated temperature is lower than the second elevatedtemperature.

Referring to FIGS. 1 and 2B, the method 100 proceeds to operation 106with forming a first orientation layer 208. In the example of theorientation material is formed of the polymers 302 and 304 with respectto FIG. 3, as illustrated in FIG. 2B, an orientation layer 208 is formedon the top surface 203 of the substrate by baking the substrate totemperature between about 80° C. and about 150° C., wherein theorientation layer 208 is formed of the first polymer 302 (loweractivation energy). In some embodiments, during the formation of theorientation layer 208, another portion (higher activation energy) of theorientation material (i.e., the portion formed of the second polymer304) may float above the formed orientation layer 208, illustrated as210 in FIG. 2B. That is, the portion 210 has not been formed as anorientation layer yet in operation 106. In some embodiments, theorientation layer 208 may have a thickness ranging between about 5nanometers to about 10 nanometers.

The method 100 continues to operation 108 with forming a secondorientation layer. Continuing with the above example in which theorientation material is formed of the polymers in FIG. 3, a secondorientation layer 210′ that is formed of the second polymer 304 isformed on the sidewall 205 by baking the substrate to temperaturebetween about 180° C. and about 250° C. as illustrated in the embodimentof FIG. 2C.

The method 100 proceeds to operation 110 with performing a directedself-assembly (DSA) process. In some embodiments, the operation 110 mayinclude multiple processes in the following order: depositing a directedself-assembly (DSA) block copolymer (BCP) layer 212 over the firstorientation layer 208 and the second orientation layer 210 (asillustrated in FIG. 2D); applying an elevated temperature to anneal theBCP layer 212 thereby achieving segregation in the BCP layer 212 to formfirst and second polymer nanostructures, 214 and 216 (as illustrated inFIG. 2E). Generally, a BCP material includes polymers comprised of atleast two different polymer segments, and these polymer segments canassemble themselves into highly ordered structures under certainconditions, such as when they are exposed to an elevated temperature. Inthe current embodiment, the BCP layer 212 may include one or more ofpolystyrene-block-polydimethylsiloxane block copolymer (PS-b-PDMS),polystyrene-block-polymethylmethacrylate (PS-b-PMMA),polyethyleneoxide-block-polyisoprene (PEO-b-PI),polyethyleneoxide-block-polybutadiene (PEO-b-PBD),polyethyleneoxide-block-polystyrene (PEO-b-PS),polyethyleneoxide-block-polymethylmethacrylate (PEO-b-PMMA),polyethyleneoxide-block-polyethylethylene (PEO-b-PEE),polystyrene-block-polyvinylpyridine (PS-b-PVP),polystyrene-block-polyisoprene (PS-b-PI),polystyrene-block-polybutadiene (PS-b-PBD),polystyrene-block-polyferrocenyldimethylsilane (PS-b-PFS),polybutadiene-block-polyviny.

Still referring to FIGS. 1 and 2E, during the DSA process (i.e.,operation 110), by choosing the height of the pattern 204 (i.e., h₁),the height of the first orientation layer 208 (i.e., h₂), and thematerials of the BCP layer 212, the first and second polymernanostructures 214 and 216 are formed such that they have a heightapproximately same as the difference of the heights h₁ and h₂, they areparallel to each other. In the illustrated embodiment of FIG. 2E, thefirst and second polymer nanostructures 214 and 216 are aligned alongdirection X, and each of them extends in a direction (i.e., Y axis inFIG. 2E) that is parallel to the sidewall 205. However, the BCP layer212 may be formed into a variety of shapes that are regularly alignedsuch as for example, a sphere, a cylinder, a lamellae, and any suitableshape known in the art. The formed polymer nanostructures 214 and 216may be later used as a pattern for a further fabrication step. In anexample, one of the polymer nanostructures (e.g., 214) may be etchedaway and the other polymer nanostructure (e.g., 216) may be left on thesubstrate as a hard mask layer to transfer a pattern onto the substratethereby reaching a finer critical dimension (CD).

Referring now to FIG. 4, a flow chart of another method 400 of forming asemiconductor device is illustrated according to various aspects of thepresent disclosure. Additional operations can be provided before,during, and after the method 400, and some operations described can bereplaced, eliminated, or moved around for additional embodiments of themethod. The method 400 is briefly described below. Then, someembodiments of the method 400 will be described in conjunction withFIGS. 5A, 5B, 5C, 5D, 5E, and 6.

Referring to FIGS. 4 and 5A, the method 400 begins at operation 402 byproviding a substrate 502 with a pattern 504. The substrate 502 mayinclude one or more layers of material or composition. For example, thesubstrate 502 may include an elementary semiconductor, such as siliconand germanium. The substrate 502 may also include a compoundsemiconductor such as silicon carbide, gallium arsenic, indium arsenide,and indium phosphide. The substrate 502 may include an alloysemiconductor such as silicon germanium, silicon germanium carbide,gallium arsenic phosphide, and gallium indium phosphide. The substrate502 may also include an epitaxial layer. For example, the substrate 502may have an epitaxial layer overlying a bulk semiconductor. Furthermore,the substrate 502 may include a semiconductor-on-insulator (SOI)structure. For example, the substrate 502 may include a buried oxide(BOX) layer formed by a process such as separation by implanted oxygen(SIMOX) or other suitable technique, such as wafer bonding and grinding.In some other embodiments, the substrate 502 may further include a toplayer (not shown) overlaying a top surface of the substrate 502. Assuch, the top layer may include silicon oxide, silicon nitride,oxynitride, silicon carbide, titanium oxide, titanium nitride, tantalumoxide, tantalum nitride, and/or any suitable materials.

In the illustrated embodiment of FIG. 5A, pattern 504 may be a resistlayer (e.g., a photoresist layer). The resist layer may be a positiveresist or a negative resist, and may be a resist suitable for deepultraviolet (DUV), extreme ultraviolet (EUV), electron beam (e-beam),and/or other lithography processes. In some specific embodiments,pattern 504 is formed of organic materials. While still falling withinthe scope of the present disclosure, the pattern 504 may be formed ofone of a variety of materials that is suitable for forming a pattern.The pattern 504 may be formed by any suitable methods such as forexample, a chemical vapor deposition (CVD) process, an atomic layerdeposition (ALD) process, a spin-on coating, and/or any combinationthereof.

Referring still to FIG. 5A, the substrate 502 includes an exposed topsurface 503, and the pattern 504 includes a sidewall 505. According tothe current embodiments, the top surface 503 of the substrate 502 andthe sidewall 505 of the pattern 504 each includes a different surfacecharacteristic. For example, the top surface 503 includes an oxidizedsurface which is more reactive to a functional group (e.g., a hydroxylgroup) while the sidewall 505 includes a surface that is formed oforganic materials which is less reactive to the hydroxyl group but morereactive to another functional group (e.g., an aromatic group).

Referring to FIG. 4, the method 400 proceeds to operation 404 byproviding an orientation material that is formed of at least twopolymers (e.g., a first polymer and a second polymer). In an embodiment,as illustrated in FIG. 6, the orientation material includes a firstpolymer 602 and a second polymer 604. More specifically, the firstpolymer 602 includes a polymer backbone 602′ and the polymer backbone602′ is terminated with a functional group 603; and the second polymer604 includes a polymer backbone 604′ and the polymer backbone 604′ isterminated with a functional group 605. The functional group 603includes at least a hydroxyl group, a carboxyl group, and/or an amidegroup; the functional group 605 includes at least an aromatic group.

Referring to FIGS. 4 and 5B, the method 400 proceeds to operation 406with forming a first orientation layer 508. In the example of theorientation material is formed of the polymers 602 and 604 with respectto FIG. 6, as illustrated in FIG. 5B, an orientation layer 508 is formedon the top surface 503 of the substrate, wherein the orientation layer508 is formed of the first polymer 602. In some embodiments, during theformation of the orientation layer 508, another portion of theorientation material (i.e., the portion formed of the second polymer604) may float above the formed orientation layer 508, which isillustrated as 510 in FIG. 5B. That is, the portion 510 has not beenformed as an orientation layer yet in operation 406. In someembodiments, the orientation layer 508 may have a thickness rangingbetween about 5 nanometers to about 10 nanometers.

The method 400 continues to operation 408 with forming a secondorientation layer. Continuing with the above example in which theorientation material is formed of the polymers in FIG. 6, a secondorientation layer 610′ that is formed of the second polymer 604 isformed on the sidewall 605 by baking the substrate to temperaturebetween about 180° C. and about 250° C. as illustrated in the embodimentof FIG. 5C.

The method 400 proceeds to operation 410 with performing a directedself-assembly (DSA) process. In some embodiments, the operation 410 mayinclude multiple processes in the following order: depositing a directedself-assembly (DSA) block copolymer (BCP) layer 512 over the firstorientation layer 508 and the second orientation layer 510 (asillustrated in FIG. 5D); applying an elevated temperature to anneal theBCP layer 512 thereby achieving segregation in the BCP layer 512 to formfirst and second polymer nanostructures, 514 and 516 (as illustrated inFIG. 5E). Generally, a BCP material includes polymers comprised of atleast two different polymer segments, and these polymer segments canassemble themselves into highly ordered structures under certainconditions, such as when they are exposed to an elevated temperature. Inthe current embodiment, the BCP layer 512 may include one or more ofpolystyrene-block-polydimethylsiloxane block copolymer (PS-b-PDMS),polystyrene-block-polymethylmethacrylate (PS-b-PMMA),polyethyleneoxide-block-polyisoprene (PEO-b-PI),polyethyleneoxide-block-polybutadiene (PEO-b-PBD),polyethyleneoxide-block-polystyrene (PEO-b-PS),polyethyleneoxide-block-polymethylmethacrylate (PEO-b-PMMA),polyethyleneoxide-block-polyethylethylene (PEO-b-PEE),polystyrene-block-polyvinylpyridine (PS-b-PVP),polystyrene-block-polyisoprene (PS-b-PI),polystyrene-block-polybutadiene (PS-b-PBD),polystyrene-block-polyferrocenyldimethylsilane (PS-b-PFS),polybutadiene-block-polyviny.

Still referring to FIGS. 4 and 5E, during the DSA process (i.e.,operation 510), by choosing the height of the pattern 504 (i.e., h₁),the height of the first orientation layer 508 (i.e., h₂), and thematerials of the BCP layer 512, the first and second polymernanostructures 514 and 516 are formed such that they have a heightapproximately same as the difference of the heights h₁ and h₂, they areparallel to each other. In the illustrated embodiment of FIG. 5E, thefirst and second polymer nanostructures 514 and 516 are aligned alongdirection X, and each of them extends in a direction (i.e., Y axis inFIG. 5E) that is parallel to the sidewall 505. However, the BCP layer512 may be formed into a variety of shapes that are regularly alignedsuch as for example, a sphere, a cylinder, a lamellae, and any suitableshape known in the art. The formed polymer nanostructures 514 and 516may be later used as a pattern for a further fabrication step. In anexample, one of the polymer nanostructures (e.g., 514) may be etchedaway and the other polymer nanostructure (e.g., 516) may be left on thesubstrate as a hard mask layer to transfer a pattern onto the substratethereby reaching a finer critical dimension (CD).

Referring now to FIG. 7, a flow chart of yet another method 700 offorming a semiconductor device is illustrated according to variousaspects of the present disclosure. Additional operations can be providedbefore, during, and after the method 700, and some operations describedcan be replaced, eliminated, or moved around for additional embodimentsof the method. The method 700 is briefly described below. Then, someembodiments of the method 700 will be described in conjunction withFIGS. 8A, 8B, 8C, 8D, 8E, 8F, and 9.

Referring to FIGS. 7 and 8A, the method 700 begins at operation 702 byproviding a substrate 802 with a pattern 804. The substrate 802 mayinclude one or more layers of material or composition. For example, thesubstrate 802 may include an elementary semiconductor, such as siliconand germanium. The substrate 802 may also include a compoundsemiconductor such as silicon carbide, gallium arsenic, indium arsenide,and indium phosphide. The substrate 802 may include an alloysemiconductor such as silicon germanium, silicon germanium carbide,gallium arsenic phosphide, and gallium indium phosphide. The substrate802 may also include an epitaxial layer. For example, the substrate 802may have an epitaxial layer overlying a bulk semiconductor. Furthermore,the substrate 802 may include a semiconductor-on-insulator (SOI)structure. For example, the substrate 802 may include a buried oxide(BOX) layer formed by a process such as separation by implanted oxygen(SIMOX) or other suitable technique, such as wafer bonding and grinding.In some other embodiments, the substrate 802 may further include a toplayer (not shown) overlaying a top surface of the substrate 802. Assuch, the top layer may include silicon oxide, silicon nitride,oxynitride, silicon carbide, titanium oxide, titanium nitride, tantalumoxide, tantalum nitride, and/or any suitable materials.

In the illustrated embodiment of FIG. 8A, pattern 804 may be a resistlayer (e.g., a photoresist layer). The resist layer may be a positiveresist or a negative resist, and may be a resist suitable for deepultraviolet (DUV), extreme ultraviolet (EUV), electron beam (e-beam),and/or other lithography processes. In some specific embodiments,pattern 804 is formed of organic materials. While still falling withinthe scope of the present disclosure, the pattern 804 may be formed ofany of a variety of materials that is suitable for forming a pattern.The pattern 804 may be formed by any suitable methods such as forexample, a chemical vapor deposition (CVD) process, an atomic layerdeposition (ALD) process, a spin-on coating, and/or any combinationthereof.

Referring still to FIG. 8A, the substrate 802 includes an exposed topsurface 803, and the pattern 804 includes a sidewall 805. In someembodiments, the top surface 803 of the substrate 802 and the sidewall805 of the pattern 804 each includes a different surface characteristic.However, in some alternative embodiments, the top surface 803 of thesubstrate 802 and the sidewall 805 of the pattern 804 may each have asubstantial similar surface characteristic.

The method continues in operation 704 with applying a treatment 807 onthe substrate 802 (more specifically, on the top surface 803 of thesubstrate), as illustrated in FIG. 8B. In some embodiments, thetreatment 807 may include a plasma-assisted dry etching process byflowing N₂/H₂ and/or O₂. The etching process may be performed attemperature ranging from about 0° C. to about 80° C. and at pressureranging from about 10 millitorr (mT) to about 60 mT. As illustrated inFIG. 8B, the etching process (i.e., 807) may be an anisotropic process(perpendicular to the top surface 803) and thus only the top surface istreated or only the top surface's surface characteristic is changedwhile the sidewall 805 remains intact. As such, after the treatment 807,the top surface 803 may include a hydrophilic surface while the sidewall805 may include a hydrophobic surface.

Referring to FIG. 7, the method 700 proceeds to operation 706 withproviding an orientation material that is formed of at least twopolymers (e.g., a first polymer and a second polymer). In an embodiment,as illustrated in FIG. 9, the orientation material includes a firstpolymer 902 and a second polymer 904. More specifically, the firstpolymer 902 includes a polymer backbone 902′ and the polymer backbone902′ is terminated with a functional group 903; and the second polymer904 includes a polymer backbone 904′ and the polymer backbone 904′ isterminated with a functional group 905. The functional group 903 is ahydrophilic group that is selected form a group consisting of a hydroxylgroup, a carboxyl group, and an amide group; the functional group 905 isa hydrophobic group that is selected form a group consisting of a ketonegroup and an ether group.

Referring to FIGS. 7 and 8B, the method 700 proceeds to operation 708with forming a first orientation layer 808. In the example of theorientation material is formed of the polymers 902 and 904 with respectto FIG. 9, as illustrated in FIG. 8C, an orientation layer 808 is formedon the top surface 803 of the substrate, wherein the orientation layer808 is formed of the first polymer 902. By applying the treatment 807 onthe substrate, the first polymer 902 terminated with the functionalgroup 903 that includes a hydrophilic group may be more reactive toattach to the top surface 803 while the portion of the orientationmaterial formed of the second polymer 905 may float above theorientation layer 808. That is, during the formation of the orientationlayer 808, another portion of the orientation material (i.e., theportion formed of the second polymer 904) may float above the formedorientation layer 808, which is illustrated as 810 in FIG. 8B. In someembodiments, the portion 810 has not been formed as an orientation layeryet in operation 708. In some embodiments, the orientation layer 808 mayhave a thickness ranging between about 5 nanometers to about 10nanometers.

The method 700 continues to operation 710 with forming a secondorientation layer. Continuing with the above example in which theorientation material is formed of the polymers in FIG. 9, a secondorientation layer 810′ that is formed of the second polymer 904 isformed on the sidewall 805 by baking the substrate to temperaturebetween about 180° C. and about 250° C. as illustrated in the embodimentof FIG. 8D.

The method 700 proceeds to operation 712 with performing a directedself-assembly (DSA) process. In some embodiments, the operation 712 mayinclude multiple processes in the following order: depositing a directedself-assembly (DSA) block copolymer (BCP) layer 812 over the firstorientation layer 808 and the second orientation layer 810 (asillustrated in FIG. 8E); applying an elevated temperature to anneal theBCP layer 812 thereby achieving segregation in the BCP layer 812 to formfirst and second polymer nanostructures, 814 and 816 (as illustrated inFIG. 8F). Generally, a BCP material includes polymers comprised of atleast two different polymer segments, and these polymer segments canassemble themselves into highly ordered structures under certainconditions, such as when they are exposed to an elevated temperature. Inthe current embodiment, the BCP layer 812 may include one or more ofpolystyrene-block-polydimethylsiloxane block copolymer (PS-b-PDMS),polystyrene-block-polymethylmethacrylate (PS-b-PMMA),polyethyleneoxide-block-polyisoprene (PEO-b-PI),polyethyleneoxide-block-polybutadiene (PEO-b-PBD),polyethyleneoxide-block-polystyrene (PEO-b-PS),polyethyleneoxide-block-polymethylmethacrylate (PEO-b-PMMA),polyethyleneoxide-block-polyethylethylene (PEO-b-PEE),polystyrene-block-polyvinylpyridine (PS-b-PVP),polystyrene-block-polyisoprene (PS-b-PI),polystyrene-block-polybutadiene (PS-b-PBD),polystyrene-block-polyferrocenyldimethylsilane (PS-b-PFS),polybutadiene-block-polyviny.

Still referring to FIGS. 7 and 8F, during the DSA process (i.e.,operation 712), by choosing the height of the pattern 804 (i.e., h₁),the height of the first orientation layer 808 (i.e., h₂), and thematerials of the BCP layer 812, the first and second polymernanostructures 814 and 816 are formed such that they have a heightapproximately same as the difference of the heights h₁ and h₂, they areparallel to each other. In the illustrated embodiment of FIG. 8F, thefirst and second polymer nanostructures 814 and 816 are aligned alongdirection X, and each of them extends in a direction (i.e., Y axis inFIG. 8F) that is parallel to the sidewall 805. However, the BCP layer812 may be formed into a variety of shapes that are regularly alignedsuch as for example, a sphere, a cylinder, a lamellae, and any suitableshape known in the art. The formed polymer nanostructures 814 and 816may be later used as a pattern for a further fabrication step. In anexample, one of the polymer nanostructures (e.g., 814) may be etchedaway and the other polymer nanostructure (e.g., 816) may be left on thesubstrate as a hard mask layer to transfer a pattern onto the substratethereby reaching a finer critical dimension (CD).

Although in the above discussion and embodiments, the first polymer(e.g., 303, 603, and 903) is to form the first orientation layer on thetop surface of the substrate (e.g., 203, 503, and 803) first and thenthe second polymer (e.g., 305, 605, and 905) is to form the secondorientation layer on the sidewall of the pattern (e.g., 205, 505, and805), in some alternative embodiments, the first orientation layerformed of the first polymer may be formed on the sidewall of the patternfirst and the second orientation layer formed of the second polymer maybe later formed on the top surface of the substrate. For example, if thesidewall 205 has a more reactive surface than the top surface 203, thefirst polymer 302 with the lower activation energy may form a firstorientation layer on the sidewall 205 by baking at a lower temperatureand then the second polymer 304 with the higher activation energy maylater from another orientation layer on the top surface by baking at ahigher temperature.

Although not intended to be limiting, one or more embodiments of thepresent disclosure provide many benefits to a semiconductor device andthe formation thereof. For example, embodiments of the presentdisclosure provide methods for forming densely packed DSA patterns withuniformity and precision by using only one orientation material for aDSA process. In some embodiments, the orientation material may be formedinto two orientation layers and each of the orientation layers isconfigured to guide a DSA process of one of the polymer segments of aBCP material. Without requiring a complicated patterning process and/oran additional material, such two orientation layers may be formed onrespective surface. Additionally, embodiments of the present disclosurecan be easily integrated into existing fabrication flow. In addition,even though two DSA processes are illustrated above, embodiments of thepresent disclosure may include more than two DSA processes where onebuilds upon another accumulatively.

In one exemplary aspect, the present disclosure is directed to a methodof forming a semiconductor device. The method includes forming apatterned feature over a substrate; applying an orientation materialthat includes a first polymer and a second polymer over the substrate,wherein the first polymer has a first activation energy and the secondpolymer has a second activation energy; baking the substrate at firsttemperature thereby forming a first orientation layer that includes thefirst polymer; baking the substrate at second temperature therebyforming a second orientation layer that includes the second polymer; andperforming a directed self-assembly (DSA) process over the first and thesecond orientation layers.

In another exemplary aspect, the present disclosure is directed to amethod of forming a semiconductor device. The method includes providinga substrate having a patterned feature formed thereon; applying anorientation material that includes a first polymer and a second polymerover the substrate, wherein the first polymer is terminated with a firstfunctional group and the second polymer is terminated with a secondfunctional group; forming a first orientation layer that includes thefirst polymer on the substrate and forming a second orientation layerthat includes the second polymer on the patterned feature; andperforming a directed self-assembly (DSA) process over the first and thesecond orientation layers.

In another exemplary aspect, the present disclosure is directed to amethod of forming a semiconductor device. The method includes providinga substrate having a patterned feature formed thereon; treating thesubstrate thereby causing a first portion of the substrate to behydrophilic; applying an orientation material that includes a firstpolymer and a second polymer over the substrate, wherein the firstpolymer is terminated with a first functional group and the secondpolymer is terminated with a second functional group; forming a firstorientation layer that includes the first polymer over the first portionof the substrate and forming a second orientation layer that includesthe second polymer over the patterned feature; and performing a directedself-assembly (DSA) process over the first and the second orientationlayers.

The foregoing outlines features of several embodiments so that those ofordinary skill in the art may better understand the aspects of thepresent disclosure. Those of ordinary skill in the art should appreciatethat they may readily use the present disclosure as a basis fordesigning or modifying other processes and structures for carrying outthe same purposes and/or achieving the same advantages of theembodiments introduced herein. Those of ordinary skill in the art shouldalso realize that such equivalent constructions do not depart from thespirit and scope of the present disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the present disclosure.

What is claimed is:
 1. A method comprising: providing a substrate havinga patterned feature formed thereon; wherein a sidewall of the patternedfeature is hydrophobic; applying an orientation material that includes afirst polymer and a second polymer over the substrate, wherein the firstpolymer is terminated with a first functional group and the secondpolymer is terminated with a second functional group; forming a firstorientation layer that includes the first polymer on the substrateincluding baking the substrate at a first temperature; wherein a portionof the orientation material formed of the second polymer floats abovethe first orientation layer; forming a second orientation layer from thefloating portion of the orientation material that includes the secondpolymer directly on the sidewall of the patterned feature and directlyover the first orientation layer, the forming of the second orientationlayer including baking the substrate at a second temperature higher thanthe first temperature; and performing a directed self-assembly (DSA)process over the first and the second orientation layers.
 2. A methodcomprising: providing a substrate having a patterned feature formedthereon; treating the substrate thereby causing a first portion of thesubstrate to be hydrophilic, wherein a sidewall of the patterned featureis hydrophobic; applying an orientation material that includes a firstpolymer and a second polymer over the substrate, wherein the firstpolymer is terminated with a first functional group and the secondpolymer is terminated with a second functional group; forming a firstorientation layer that includes the first polymer over the first portionof the substrate including baking the substrate at a first temperature;wherein a portion of the orientation material formed of the secondpolymer floats above the first orientation layer; forming a secondorientation layer from the floating portion of the orientation materialthat includes the second polymer directly on a sidewall of the patternedfeature and directly over the first orientation layer, the forming ofthe second orientation layer including baking the substrate at a secondtemperature higher than the first temperature; and performing a directedself-assembly (DSA) process over the first and the second orientationlayers.
 3. The method of claim 2, wherein the first functional groupincludes a hydrophilic group that is selected from the group consistingof a hydroxyl group, a carboxyl group, and an amide group.
 4. The methodof claim 2, wherein the second functional group includes a hydrophobicgroup that is selected from the group consisting of a ketone group andan ether group.
 5. The method of claim 2, wherein treating the substrateincludes applying a plasma-assisted dry etching process by flowing N₂/H₂and/or O₂.
 6. The method of claim 5, wherein applying theplasma-assisted dry etching process includes applying theplasma-assisted dry etching process at a temperature ranging from about0° C. to about 80° C. and at pressure ranging from about 10 millitorr(mT) to about 60 mT.
 7. The method of claim 2, wherein the performingthe DSA process includes: depositing a copolymer material over the firstand the second orientation layers, wherein the copolymer material isdirected self-assembling; and inducing microphase separation within thecopolymer material thereby defining a first constituent of the copolymermaterial and a second constituent of the copolymer material; wherein thecopolymer material includes one or more materials from the groupconsisting of polystyrene-block-polydimethylsiloxane block copolymer(PS-b-PDMS), polystyrene-block-polymethylmethacrylate (PS-b-PMMA),polyethyleneoxide-block-polyisoprene (PEO-b-PI),polyethyleneoxide-block-polybutadiene (PEO-b-PBD),polyethyleneoxide-block-polystyrene (PEO-b-PS),polyethyleneoxide-block-polymethylmethacrylate (PEO-b-PMMA),polyethyleneoxide-block-polyethylethylene (PEO-b-PEE),polystyrene-block-polyvinylpyridine (PS-b-PVP),polystyrene-block-polyisoprene (PS-b-PI),polystyrene-block-polybutadiene (PS-b-PBD),polystyrene-block-polyferrocenyldimethylsilane (PS-b-PFS),polybutadiene-block-polyvinylpyridine (PBD-b-PVP), andpolyisoprene-block-polymethylmethacrylate (PI-b-PMMA).
 8. A methodcomprising: providing a substrate having a patterned feature formedthereon; treating the substrate thereby causing a portion of thesubstrate to be hydrophilic, wherein a sidewall of the patterned featureis hydrophobic; applying an orientation material that includes a firstpolymer and a second polymer over the substrate, wherein the firstpolymer is terminated with a first functional group and the secondpolymer is terminated with a second functional group; forming a firstorientation layer that includes the first polymer over a first portionof the substrate including baking the substrate at a first temperature;wherein a portion of the orientation material formed of the secondpolymer floats above the first orientation layer; forming a secondorientation layer from the floating portion of the orientation materialthat includes the second polymer directly on a sidewall of the patternedfeature and directly over the first orientation layer, the forming ofthe second orientation layer including baking the substrate at a secondtemperature higher than the first temperature; and performing a directedself-assembly (DSA) process over the first and the second orientationlayers.
 9. The method of claim 8, wherein treating the substrateincludes applying a plasma-assisted dry etching process to the substrateto cause the portion of the substrate to be hydrophilic.
 10. The methodof claim 9, wherein the plasma-assisted dry etching process includesflowing N₂/H₂ onto the substrate.
 11. The method of claim 9, wherein theplasma-assisted dry etching process includes flowing O₂ onto thesubstrate.
 12. The method of claim 8, wherein the first functional groupincludes a hydrophilic group that is selected from the group consistingof a hydroxyl group, a carboxyl group, and an amide group, and whereinthe second functional group includes a hydrophobic group that isselected from the group consisting of a ketone group and an ether group.13. The method of claim 8, wherein the performing the DSA processincludes: depositing a copolymer material over the first and the secondorientation layers, wherein the copolymer material is directedself-assembling; and inducing separation within the copolymer materialthereby defining a first constituent of the copolymer material and asecond constituent of the copolymer material.
 14. The method of claim 1,further comprising forming a second patterned feature on the substrate.15. The method of claim 14, wherein the first orientation layer isformed on the substrate between a first sidewall of the patternedfeature and a second sidewall of the second patterned feature.
 16. Themethod of claim 15, wherein the second orientation layer is formed onthe first sidewall of the patterned feature.
 17. The method of claim 16,further comprising forming a third orientation layer on the secondsidewall of the second patterned feature.
 18. The method of claim 17,wherein a first end of the second orientation layer and a second end ofthe third orientation layer physically contact an upper surface of thefirst orientation layer.